package Demo03;

import java.util.Stack;

class MyQueue {
    private Stack<Integer> stack1;
    private Stack<Integer> stack2;
    public MyQueue() {
        stack1 = new Stack();
        stack2 = new Stack();
    }

    public void push(int x) {
        stack1.push(x);
    }

    public int pop() {
        if(!stack2.isEmpty()) {
            return stack2.pop();
        } else if(stack2.isEmpty()&&!stack1.isEmpty()) {            while (!stack1.isEmpty()) {
            stack2.push(stack1.pop());
        }
            return stack2.peek();
        } else {
            return -1;
        }

    }

    public int peek() {
        if(!stack2.isEmpty()) {
            return stack2.peek();
        } else if(stack2.isEmpty()&&!stack1.isEmpty()) {
            while (!stack1.isEmpty()) {
                stack2.push(stack1.pop());
            }
            return stack2.peek();
        } else {
            return -1;
        }
    }

    public boolean empty() {
        return stack1.isEmpty()&&stack2.isEmpty();
    }
}
